Can the values ​​of `stdin`,` stdout` and `stderr` be considered constant?

From the Ubuntu man page stdin(3)

:

extern FILE *stdout;

      

        
        
        
      

    

From the mingw64 file stdio.h

:

#define stdout (&__iob_func()[1])

      

        
        
        
      

    

Both assume that the value stdout

(pointer) cannot be considered constant.

Can I still rely on something like this:

FILE * stream;

// early after startup
stream = stdout;

// much later, far down the stack, in a different function
fprintf(stream, "%s", "fprintf(stream, \"");